Incorporation of replaceable cylinder liners in the design of an internal combustion engine provides numerous advantages to the manufacture and user of such an engine. In addition to the obvious benefit of allowing such liners to be replaced during overhaul of the engine without replacement of the entire cylinder block, cylinder liners eliminate the necessity to scrap the entire block during manufacture or use should the inside surface of one cylinder being improperly machined or otherwise damaged. Despite this and other advantages, numerous problems attend the use of replaceable cylinder liners as is exemplified by the great variety of liner designs previously used by engine manufacturers. Further, seals are prevalent throughout many diesel engine platforms, or configurations, and it is often desirable, or necessary, to maintain separation between fluids within the engine and the environment. This is particularly the case between combustion gasses within the cylinder liner and coolant surrounding the cylinder liner. With conventional cylinder liner configurations, a combustion gas seal is provided to prevent combustion gasses from passing from the combustion chamber between the cylinder liner and cylinder head. Should this seal fail, the combustion gasses may mix with the coolant of the coolant jacket surrounding the cylinder liner. A combustion gas seal of this type for providing a combustion gas seal between the top surface of the cylinder liner and the cylinder head is set forth in U.S. Pat. No. 6,036,194 issued to Stamper and assigned to the assignee of the subject invention.
Presently, both wet and dry type cylinder liners incorporate either a mid-stop arrangement wherein the cylinder liner is substantially supported within the block mid-way along the length of the cylinder liner or a top stop wherein the cylinder liner is supported about an upper periphery thereof. U.S. Pat. No. 3,403,661 discloses a liner design for use in an engine block having a counter bore cylinder cavity wherein the liner includes a radially outwardly extending flange designed to be seated in the counter bore so that the liner may be easily clamped into place by the engine cylinder head. In order to provide for coolant flow around the liner, a seal is provided between the engine block and a lower portion of the liner spaced from the top flange. Due to vibration and thermally induced size changes of the liner, relative motion occurs in the seal area of a type which may destroy conventionally known seals.
It is known in the industry to employ mechanical means to obtain a seal between the cylinder liner and cylinder block to prevent the passage of coolant at the joint between the cylinder block and the cylinder liner. One such approach is set forth in U.S. Pat. No. 4,244,330 issued to Baugh et al. and assigned to the assignee of the subject invention. Therein, the cylinder liner for an internal combustion engine includes a cylindrical hollow body having a press-fitted upper end and a stop located intermediate the liner ends for engaging an engine block liner stop to provide upper and lower seals for a coolant passage. The outside surfaces of the liner adjacent the press-fitted upper end and the stop are formed to permit a settable plastic material to be used between the liner and engine block to assist in forming the coolant seal and to provide radial support of the cylinder liner.
Similarly, U.S. Pat. No. 5,979,374 provides a replaceable cylinder liner for a cylinder cavity within a cylinder block of an internal combustion engine having a liner stop positioned within the cavity at a point intermediate the extremes of travel of a piston disposed for reciprocating travel within the cylinder cavity. The liner includes a hollow cylinder body having an inner end portion and an outer end portion with the outer end portion having a piston engaging inside surface for guiding the piston during travel and a top end face for forming a combustion gas seal with an engine head. The liner further includes a mechanism for reinforcing and securing the liner in place within the cylinder cavity and for resisting deforming forces resulting from fuel combustion within the outer end portion and for compressively and frictionally engaging an inside surface of the cylinder cavity when pressed therein. The reinforcing and securing mechanism includes an end boss adjacent an outer end of the outer end portion, an outer diameter of such end boss being slightly greater than an inside diameter of corresponding portions of the cylinder cavity into which the end boss is press fitted. The replaceable liner further includes a liner support for axially supporting the hollow cylindrical body within the cylinder cavity with the liner support including a liner stop engaging surface for engaging the liner stop when the liner is placed within the cylinder cavity.
At an outermost end of the outer end portion of the liner is the end boss which is formed on an outer surface of the liner for reinforcing and primarily for frictionally engaging the inside surface of the cylinder cavity to form a coolant seal and for resisting the deforming forces resulting from fuel combustion within the hollow cylindrical body. Particularly, the end boss prevents radial movement of the outer end portion of the cylinder liner while permitting limited axial movement of the outer end portion within the liner receiving cavity by forming a radial press fit with the inside surface of the liner receiving cavity by compressively and frictionally engaging the inside surface of such cavity when pressed therein. Formed in an outer surface of the end boss are one or more recesses for receiving one or more o-ring type sealing members which provide a coolant seal between the end boss and the adjacent cylinder block. During routine maintenance of in the event of an engine overhaul in order to replace one or more of the o-ring type sealing members, it is necessary to undertake the removal of each cylinder liner to access the o-ring seal.